1. Field of Invention
This invention relates generally to the formation of a patterned layer of material on a substrate, and more particularly to the formation of a circuitized conductor pattern on a dielectric material. In even more particular aspects, this invention relates to utilizing a photoimageable dielectric material as a substrate and using photo imaging techniques to both pattern the conductor material and also to provide openings or vias through such dielectric material for forming electrical connection to the circuitized pattern.
2. Description of the Prior Art
There have been many different techniques for forming circuit patterns on various types of dielectric substrates. Certain of these techniques employ a dielectric substrate on to which a layer of metal is applied. Photoimaging techniques utilizing photoresists are used in various ways to pattern the layer of conductive metal which is then etched to form a pattern of the desired circuit configuration. In some instances through holes or vias are required which extend through the dielectric substrate to allow formation of electrical contacts such as by solder balls to the underside of various locations of the circuitized conductive material. Frequently the required end product is a flexible type circuit which requires a thin film of flexible dielectric material which has provided thereon a thin film of flexible patterned metal as a circuit.
Some representative techniques for forming such patterns are shown in IBM Technical Disclosure Bulletin Volume 15 No. 2, July 1972, page 420, IBM Technical Disclosure Bulletin Volume 31 No. 6, November 1988, page 144, U.S. Pat. No. 4,512,843 assigned to Sumitomo Metal Mining Company Limited, and U.S. Pat. No. 4,911,786 assigned International Business Machines Corporation, assignee of the present invention.